Stress testing begins on Bay Bridge

The entire Bay Bridge remains closed with no definite time of reopening while repairs continue on the span.

The entire Bay Bridge remains closed with no definite time of reopening while repairs continue on the span.

Photo: Michael Macor, The Chronicle

Photo: Michael Macor, The Chronicle

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The entire Bay Bridge remains closed with no definite time of reopening while repairs continue on the span.

The entire Bay Bridge remains closed with no definite time of reopening while repairs continue on the span.

Photo: Michael Macor, The Chronicle

Stress testing begins on Bay Bridge

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Workers finally began testing a patch on the closed Bay Bridge on Saturday night after days of struggling to fix a cracked piece of steel.

The progress means there is a glimmer of hope that the bridge could reopen in time for Monday's commute.

Still, Caltrans officials warned that the necessary stress tests could lead to more construction work to make sure the repair can withstand high winds and vibrations - the conditions engineers blame for breaking the original fix.

More than 5,000 pounds of metal came crashing down onto traffic Tuesday evening, totaling a couple cars but leaving the drivers largely unscathed. The bridge has been closed ever since, the longest closure since the 1989 Loma Prieta earthquake shut it for a month.

"Once it's deemed safe, that's when it will open," said Lauren Wonder, a Caltrans spokeswoman. "At this point, I can't give you an estimate until we get a better sense of where the stress testing is."

Workers test the patch by slowly tightening steel rods that keep the brace secure. Then anti-vibration crossbeams are installed. After that, the rounds of final inspections begin.

Inspectors hired by Caltrans will evaluate the work, followed by a group of independent inspectors who check it again. They may drive several large trucks over the bridge to test the vibrations, agency spokesman Bart Ney said.

Crews have been working day and night trying to repair the eastern cantilevered span where a cracked eyebar was found about two months ago. A quick fix was installed over Labor Day weekend, but engineers failed to appropriately factor how weather and traffic would affect the repair.

The new fix isn't a vast departure from the original design; rather, it includes modifications designed to keep the brace from jiggling around. On Saturday, crews ground the sides of metal holes designed for large nuts that stabilize the original repair. They installed the nuts, checked the alignment, then removed them again to make further adjustments, Ney said.

If the newest repair should break, officials said, pieces of metal have been attached to the bridge to keep the patch from falling.

Caltrans plans to increase routine inspections of the bridge and the repair. Monitors will be installed to watch for unwanted movement that could cause another failure.

The bridge's closure has meant record-breaking numbers of riders on BART and clogged freeways that lead to alternate bridges.

BART ran trains through the night Friday and Saturday. Trains weren't terribly crowded Saturday morning and afternoon, though the BART stations were busier than usual and parking was tough to come by at some East Bay spots.